Further improvement in performance of magnetic heads has been required along with an increase in recording density of magnetic recording/reproducing apparatuses. As magnetic heads, widely used is a composite-type magnetic head having a multilayer structure of a magnetic detecting element such as magneto-resistive (MR) element and a magnetic recording element such as electromagnetic coil element, and with these elements, data signals can be recorded on or read from a magnetic disk that is a magnetic recording medium.
The magnetic recording medium is a sort of discontinuous body of aggregated magnetic fine particles, and each magnetic fine particle has a single-domain structure. It should be noted that each recording bit comprises a plurality of magnetic fine particles. In order to increase the recording density, therefore, irregularities at boundaries of recording bits have to be reduced by reducing the size of the magnetic fine particles. However, reducing the size of the magnetic fine particles causes a problem of decreasing thermal stability of magnetization along with a decrease in volume.
An index of the thermal stability of magnetization is given by KUV/kBT. In this, KU is a magnetic anisotropy energy of the magnetic fine particles, V is a volume of one magnetic fine particle, kB is a Boltzmann constant, and T is an absolute temperature. Reducing the size of the magnetic fine particles means reducing the volume V of the magnetic fine particle, which leads to lowering KUV/kBT to thereby impair the thermal stability.
Although the magnetic anisotropy energy KU may be increased at the same time as measures against this problem, the increase in the magnetic anisotropy energy KU enhances the coercivity of the recording medium. On the other hand, the intensity of a writing magnetic field generated by a magnetic head is substantially determined by the saturated magnetic flux density of a soft magnetic material constituting a magnetic pole within the head. Therefore, no writing can be made if the coercivity exceeds a permissible value determined by the limit of the writing magnetic field intensity.
As a method for solving such a problem in thermal stability of magnetization, proposed is a so-called thermally assisted magnetic recording method in which although a magnetic material having a large magnetic anisotropy energy KU is employed, writing is performed after reducing the coercivity such that heat is applied to a recording medium immediately before application of a writing magnetic field. This method is similar to magneto-optical recording but different in that spatial resolution in the thermally assisted recording depends on magnetic field while spatial resolution in the magneto-optical recording depends on light.
In practice, the magnetic recording medium is typically heated by irradiating the magnetic recording medium with a light such as near-field light. In this method, it is important where and how a high power light source is disposed in the magnetic head so as to stably apply a sufficiently intense light to a desired area of the magnetic recording medium. As for the setting of the light source, for example, U.S. Pat. No. 7,538,978) discloses a configuration in which a laser unit including a laser diode is disposed on a back surface of a slider, and US Patent Application No. 2008/0056073 A1 discloses a configuration in which a structure of a laser diode element with a monolithically integrated reflection mirror is disposed on a back surface of a slider. Furthermore, US Patent Application No. 2005/0213436 A1 discloses a slider that is formed together with a semiconductor laser, and Robert E. Rottmayer et al. “Heat-Assisted Magnetic Recording” IEEE TRANSACTIONS ON MAGNETICS, Vol. 42, No. 10, p. 2417-2421 (2006) discloses a configuration in which a diffraction grating is irradiated with a light generated from a laser unit provided within a drive apparatus.
In any case, the thermally assisted magnetic head has to be mounted on a suspension. The mounting arrangement of the thermally assisted magnetic head to the suspension may be the one in which a groove is formed in a slider and a flexible part of the suspension is inserted and fixed in the groove. In realizing this arrangement, heretofore, the groove has been formed by machining.
However, grooves that can be realized by machining are limited to those having a simple linear shape. Therefore, it is difficult to precisely insert and position the suspension in the groove. Even if it is precisely inserted and positioned, moreover, it may easily be displaced before fixing. Furthermore, a curved surface due to the shape of a tool or a processing method is left at a position where the bottom surface and the inner side face of the groove meet with each other. This curved surface tends to become an obstacle, causing a problem such as improper insertion or tilt of the suspension.